Ñîçäàíèå ôóíêöèîíàëüíûõ ìàòåðèàëîâ íîâûõ òèïîâ èëè îáëàäàþùèõ íîâûìè ñâîéñòâàìè ÿâëÿåòñÿ öåíòðàëüíîé çàäà÷åé õèìèè. Ïîñêîëüêó ñâîéñòâà êîìïëåêñîâ îïðåäåëÿþòñÿ ñîâîêóïíîñòüþ ïðèðîäû öåíòðàëüíîãî èîíà ìåòàëëà è ëèãàíäà, òî çàäà÷à äèçàéíà íîâûõ ëèãàíäîâ äëÿ ïîëó÷åíèÿ êîìïëåêñîâ ñ çàäàííûìè ñâîéñòâàìè ñòîèò êàê ïåðåä îðãàíè÷åñêîé, òàê è ïåðåä õèìèåé êîîðäèíàöèîííûõ ñîåäèíåíèé.  äîêëàäå áóäóò ïðåäñòàâëåíû ðåçóëüòàòû ìîäåëèðîâàíèÿ, ñèíòåçà è èññëåäîâàíèÿ ôóíêöèîíàëüíûõ ëèãàíäîâ äëÿ ðàñïîçíàâàíèÿ èîíîâ f-ýëåìåíòîâ, àíèîíîâ è àìèíîêèñëîò. << Ñâåðíóòü

For a long time, rare-earth (RE) intermetallic materials have attracted considerable interest because of their exotic properties at low temperatures which include complex magnetic phases, valence fluctuations, heavy-fermion states, Kondo behavior and many others. It is widely believed that all of these properties stem from the delicate interplay between almost localized 4f electrons and itinerant valence band states.

Our experiments aim to disclose details of this interaction, and reveal the fine electronic structure of such materials near the Fermi level. To this end, we apply Angle-Resolved Photoemission Spectroscopy (ARPES) technique, which in spite of its surface sensitivity when working in UV mode, indeed, allows to gain deep insight not only into surface electron structure, but to probe the bulk derived states, too. In that regard, the particular point of our experiments is the proper discrimination of (sub-) surface and bulk related phenomena.

In the past years we performed extensive ARPES studies on the RERh₂Si₂ (RE = Ce, Eu and Yb) series of compound as well as on YbIr2Si2 With our approach we were able to address some of the topics at the core of strongly correlated 4f electron systems: (i) observation of crystal-electric field (CEF) splitting of the 4f states and their fine dispersion induced by f-d hybridization; (ii) insight into the Fermi surface and manifestation of its strong 4f character. Disclosing its topology and features reflecting f-d coupling at the surface and bulk of the material. Studying its temperature dependence for a Kondo lattice (YbRh2Si2); (iii) clear evidence of the interplay of Dirac fermions and heavy quasi-particles; (iv) manifestation of unusual and strong ferromagnetism at the Si-terminated surface of an antiferromagnet (EuRh2Si2) caused by buried 4f magnetic moments of Eu lying 4-layers below the surface.

[1] A. Chikina et. al., Strong ferromagnetism at the surface of an antiferromagnet caused by buried magnetic moments, Nature Communications 5, 3171 (2014).
[2] M. Hoppner et. al., Interplay of Dirac fermions and heavy quasiparticles in solids, Nature Communications 4, 1646 (2013).
[3] S. Danzenbacher et. al., Insight into the f-derived Fermi surface of the heavy-fermion compound YbRh2Si2, Phys. Rev. Lett. 107, 267601 (2011).
[4] D.V. Vyalikh et. al., k-dependence of the crystal-field splittings of 4f states in rare-earth systems, Phys. Rev. Lett. 105, 237601 (2010).
[5] D.V. Vyalikh et. al., Tuning the hybridization at the surface of a heavy-fermion system, Phys. Rev. Lett., 103, 137601 (2009)
<< Ñâåðíóòü

Ðå÷ü ïîéäåò î âêëþ÷åíèè ðîäèÿ, èðèäèÿ, ïëàòèíû, çîëîòà, ðóòåíèÿ â ñòðóêòóðû èçîïîëè- è ãåòåðîïîëèñîåäèíåíèé (âîëüôðàìàòû, íèîáàòû, òàíòàëàòû, ôîñôî- è ñèëèêîâîëüôðàìàòû), î âîçìîæíîñòÿõ ðàçëè÷íûõ ìåòîäîâ õàðàêòåðèñòèêè òàêèõ ñîåäèíåíèé, î ñòàáèëèçàöèè íåîáû÷íûõ ñòåïåíåé îêèñëåíèÿ áëàãîðîäíîãî ìåòàëëà â òàêèõ ïðîèçâîäíûõ (íàïðèìåð, Ir(II), Ir(V)), î ïîëó÷åíèè óñòîé÷èâûõ ãèäðîëèçó ìåòàëëîîðãàíè÷åñêèõ ñîåäèíåíèé, â êîòîðûõ àòîì áëàãîðîäíîãî ìåòàëëà îáðàçóåò ñèãìà-ñâÿçè ìåòàëë-óãëåðîä è îäíîâðåìåííî êîîðäèíèðîâàí ê ôðàãìåíòó ïîëèîêñîìåòàëëàòà. << Ñâåðíóòü